Tutorial: Changing Levels Last edited 1 month ago2018-10-14 08:30:55 UTC by Penguinboy Penguinboy

A quick and dirty guide to perfect level changes

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Level changes are often over explained, and too complicated for their own good. There really is nothing to them and if you follow this tutorial step by step, you should have absolutely no trouble whatsoever.

What is a level change?

A level change is, simply put, a transition or displacement from one map (.bsp file) to another. And the reason you're reading this is because you're lost or trying to get a level change to work properly.

Why do I need level changes?

If you're thinking to yourself: "I can get by without them, and save myself a lot of hassle...", then think again!

Half-Life maps have limits. These limits should never be reached or pushed, you can read more about these in the general MAX_MAP limits part of Tommy14's errors page. If your levels are getting too big you should consider splitting them into 2 or more separate levels to avoid reaching these limits. This can be really useful for reducing r_speeds when working with two or more complex areas, or just to help you keep track of where you are in your map. Huge detailed maps are really difficult to work with in Hammer, as you probably already know.

How do I create level changes?

There are 3 types of level changes:

Seamless level changes

The only entities you'll need - since you just want a simple level change - will be trigger_changelevel (one in each map) and an info_landmark (also one in each map).

Start by making a suitable corridor:
A suitably suitable corridorA suitably suitable corridor
Now to add the info_landmark. Read very carefully is these details are critical:

The info_landmark sets up a constant point of reference in the origin and destination maps. It must appear in both maps otherwise the level change will not work correctly. The origin and destination info_landmark must both have the same Name (targetname)
Always put names of maps and info_landmarks in lowercase!!! And do not use spaces or other characters except numbers and letters, _ underscores are ok.
So basically, it's the same info_landmark in both maps.
LandmarkLandmark
The Origin map trigger_changelevel:

Set these properties you need to change:

New map name: map2
Landmark Name: landmark1 (or whatever you called your two identical landmarks - one in each map)

The Destination map trigger_changelevel:

Set these properties you need to change:

New map name: map1
Landmark Name: landmark1 (or whatever you called your two identical landmarks - one in each map)
TriggerTrigger
Now, compile the maps through hammer or any other front-end compiler but remember not to run the game!, fire up hl with the console, and test the transition. If you did this correctly you should seamlessly jump from one map to the next no matter how you enter the trigger_changelevel.

One way level changes

You would think a one way level change would only require one trigger_changelevel?

Wrong.

You have to set the level change up exactly as you would for a normal change. The difference is that in the second map, reduce the size of the trigger_changelevel brush and move it somewhere that the player cannot get to it. That is what stops the player from going back. You can also check the Use Only Flag just to make sure those NoClipping players still can't get back.

16 Comments

Commented 10 years ago2008-07-24 03:43:29 UTC Comment #100615
great tutorial ;)
Commented 10 years ago2008-08-03 13:59:00 UTC Comment #100616
When I loaded the next level, I was outside of the map. Can anyone help me? :(
Commented 10 years ago2008-10-05 20:40:54 UTC Comment #100617
couldnt be explained clearer.
Commented 9 years ago2009-01-24 19:30:37 UTC Comment #100618
it crashes when i get on the 2nd map
Commented 9 years ago2009-06-10 23:56:06 UTC Comment #100619
great tutorial thanks! i set up everything the way you said, but i get "stuck" when i arrive at map2, that is, i can't move, even with noclipping!
Commented 9 years ago2009-09-14 04:19:55 UTC Comment #100620
Why don't I have trigger_changlevel?
Commented 8 years ago2010-10-11 04:25:36 UTC Comment #100621
it crashes for me too, i cant get it to work!
Commented 7 years ago2011-02-19 06:52:39 UTC Comment #100622
If its crashing, make sure your landmarks have the SAME name, and that BOTH levels, regardless of one way or both ways, have the trigger AND a landmark. I just had that problem, and now my map works.
Commented 7 years ago2011-08-24 00:06:36 UTC Comment #100623
Also make sure you've actually compiled both maps before running the game. Yeah, that has happened to me. Twice.
Commented 3 years ago2015-03-26 22:07:25 UTC Comment #100624
Moreover this trigger_changelevel method allows the following entity persistence !
Commented 3 years ago2015-07-23 02:16:49 UTC Comment #100625
Why is it taking me back to the loading screen where I choose the player and teams?
Commented 3 years ago2015-08-17 08:15:46 UTC Comment #100626
Good tutorial it's just that I'm stuck when on the second map...
Commented 3 years ago2015-11-10 01:53:51 UTC Comment #100627
I had a problem with a levelchange, maybe it helps someone what I found out.

I have three maps and the player traverses them in this order:

Map a
Map b
Map c

The transition between Map b and Map c didn't work because the trigger_changelevel from "map a" to "map b" had a wrong "New map name", like "Map C". So I guess The Value you type in for "New map name" is Case-Sensitive.
Commented 2 years ago2016-05-24 08:40:17 UTC Comment #100628
I made two test maps for an HL mod I want create.

The transition from 1st map to 2nd map worked correctly.

But when I tried to return to 1st map, it didn't worked. Why?
Commented 2 years ago2016-05-29 11:59:17 UTC Comment #100629
alright, the level change work for me, only one issue: since my level change is in an elevator, i have npcs from the previous level who shows up in the next level, but i really dont need them in here, so how do i get rid of them?
Commented 2 years ago2016-10-01 06:17:55 UTC Comment #100630
Me works, but the npcs of the another map continue in the new map? Why?

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